For quite a few years now, we've been attempting to solve the "craters the shit out of my primers" problem that has plagued the Accuracy International bolt action setups since their conception.
-Understand that this platform was initially designed for killing people from afar by Secret Squirrel guys. This "problem" isn't a problem when used for the intended purpose. (a bit graphic, but its the truth) Operators typically aren't conducting brass calls on the battlefield and reloading in their hooches under the romantic ambiance of 220v, 50hz florescent illumination.
Its a fire and forget application and cratered primers are the least of the worries.
You reloader types are the ones who conjured up this issue.
With AI bolts this isn't the simplest problem to solve because the bolts are much harder than woodpecker lips. The material is (speculating as I really don't know for sure) case hardened via some sort of nitrogen/ammonia salt bath process. (Salt or gas, but I am pretty sure its salt based based on the surface finish)
Basically you have a hard boiled egg and that shell is not the easiest to machine with conventional tooling. The core is tough and its gummy. None of which is "tap friendly".
A description of what were doing and why:
Our process uses a vertical cnc mill. Basically all were doing is punching the striker pin hole to a larger size and threading it. With a tap this would be a "not so trivial" task. Taps don't typically don't care for "hard as f$%k" surfaces on parts. So, rather than fight the man, we thread mill the enlarged ID bore. This way we can control the threads almost infinitely and achieve the desired thread fit.
From there its pretty simple. Loctite and epoxy on a rifle bolt is gay, so we attempt to be "less gay" by soldering. Magnetic induction and a low temp solder makes this pretty easy. Finally, poke a .0625" hole down the center and your done.
Final op is to toss the pin in a tool room lathe and buzz it down to a slip fit. The relationship between striker pin and the hole is made smaller and now the striker tip extrudes less material from the primer cup during firing. No more lunar impact craters.
We've done this for years now. Not a big deal. Others have had success with it as well.
Sometime this year, Accuracy International made a change where they decided to reduce the striker pin diameter. With that introduction came a number of requests from the shooting community to use the new strikers with the legacy bolts. As I'm famous for doing, I said sure before I had the parts in my hands. Some new challenges present themselves that must be solved.
Below is a solid model of the new striker pin/bolt head assembly. New pins with the .0625" dia are much shorter in length than the old ones. The new bolts are made to suit this. Older bolts however are not. Attempting to bush an old bolt to accept a new pin doesn't work because the threaded insert will prevent the striker pin from traveling forward enough for the required .052" of pin protrusion above the bolt face. This photo of the two pins on our optical comparator shows the differences in the projected length.
(approximately
New striker installed in old bolt. Striker pin tip is below the bolt face.
If we were to attempt to shorten the threaded insert, you end up with almost no engagement in the bolt body. The distance from the face of the bolt to the 60* countersink on the inside is less than 3/32" in length. .08" is not nearly enough thread engagement for the insert.
The solution to making this work is to install the bushing as usual in the bolt to bring the hole diameter back to one that is appropriate for the new pin. The pin must then be turned to push the shoulder feature rearward so that it emulates the legacy modification we've been doing for years.
So, we can do the work, but your not going to be able to purchase new style striker pins with the expectation of them dropping into the old bolts and running to standard. The new pins still have to be machined.
Hope this helps.
C.
-Understand that this platform was initially designed for killing people from afar by Secret Squirrel guys. This "problem" isn't a problem when used for the intended purpose. (a bit graphic, but its the truth) Operators typically aren't conducting brass calls on the battlefield and reloading in their hooches under the romantic ambiance of 220v, 50hz florescent illumination.
Its a fire and forget application and cratered primers are the least of the worries.
You reloader types are the ones who conjured up this issue.
With AI bolts this isn't the simplest problem to solve because the bolts are much harder than woodpecker lips. The material is (speculating as I really don't know for sure) case hardened via some sort of nitrogen/ammonia salt bath process. (Salt or gas, but I am pretty sure its salt based based on the surface finish)
Basically you have a hard boiled egg and that shell is not the easiest to machine with conventional tooling. The core is tough and its gummy. None of which is "tap friendly".
A description of what were doing and why:
Our process uses a vertical cnc mill. Basically all were doing is punching the striker pin hole to a larger size and threading it. With a tap this would be a "not so trivial" task. Taps don't typically don't care for "hard as f$%k" surfaces on parts. So, rather than fight the man, we thread mill the enlarged ID bore. This way we can control the threads almost infinitely and achieve the desired thread fit.
From there its pretty simple. Loctite and epoxy on a rifle bolt is gay, so we attempt to be "less gay" by soldering. Magnetic induction and a low temp solder makes this pretty easy. Finally, poke a .0625" hole down the center and your done.
Final op is to toss the pin in a tool room lathe and buzz it down to a slip fit. The relationship between striker pin and the hole is made smaller and now the striker tip extrudes less material from the primer cup during firing. No more lunar impact craters.
We've done this for years now. Not a big deal. Others have had success with it as well.
Sometime this year, Accuracy International made a change where they decided to reduce the striker pin diameter. With that introduction came a number of requests from the shooting community to use the new strikers with the legacy bolts. As I'm famous for doing, I said sure before I had the parts in my hands. Some new challenges present themselves that must be solved.
Below is a solid model of the new striker pin/bolt head assembly. New pins with the .0625" dia are much shorter in length than the old ones. The new bolts are made to suit this. Older bolts however are not. Attempting to bush an old bolt to accept a new pin doesn't work because the threaded insert will prevent the striker pin from traveling forward enough for the required .052" of pin protrusion above the bolt face. This photo of the two pins on our optical comparator shows the differences in the projected length.
(approximately
New striker installed in old bolt. Striker pin tip is below the bolt face.
If we were to attempt to shorten the threaded insert, you end up with almost no engagement in the bolt body. The distance from the face of the bolt to the 60* countersink on the inside is less than 3/32" in length. .08" is not nearly enough thread engagement for the insert.
The solution to making this work is to install the bushing as usual in the bolt to bring the hole diameter back to one that is appropriate for the new pin. The pin must then be turned to push the shoulder feature rearward so that it emulates the legacy modification we've been doing for years.
So, we can do the work, but your not going to be able to purchase new style striker pins with the expectation of them dropping into the old bolts and running to standard. The new pins still have to be machined.
Hope this helps.
C.
Last edited:
